1. Field of the Invention
The invention relates to a battery cell and a power supply that is formed by welding metallic members to terminals of the battery cells.
2. Description of the Related Art
A battery cell is available in which one end of an electrode terminal is connected to an electrode unit contained in a case, and the other end of the terminal is passed through a hole formed in the case and is extended to the outside. In a battery cell with such a configuration, as described in Japanese. Patent Application Publication No. 2005-339990 (JP-A-2005-339990) for example, a resin member (insulating member) is disposed in the hole to isolate the terminal from the case.
Battery cells with such a configuration are in some cases used in a form in which another member (metallic member, for example) is welded to the electrode terminal. For example, as a power supply or a component thereof that is mounted on a vehicle as a power source or the like of the vehicle, a battery pack can be used in which a plurality of battery cells (unit cells; typically, secondary batteries, such as lithium-ion secondary batteries) are connected in series or in parallel. An example of the method of connecting a plurality of unit cells is a method, described in Japanese Patent Application Publication No. 2005-339925 (JP-A-2005-339925) for example, in which a connection member (bus bar) is welded to an electrode terminal of a unit cell. Another member is in some cases welded to the electrode terminal to connect a battery cell and an external circuit.
However, when another member is welded to the electrode terminal in this way, the resin member can melt due to increase in temperature of the resin member caused by the heat applied during welding. When the melt of the resin member progresses too much, it may become a cause of problems, such as defective insulation between the electrode terminal and the case, and defective sealing in the case.